Jules bebie



JULIEE BEBIE, OF 8'1. LOUIS, OF ST. LOUIS,

mrssouai, assmnoa 'ro monsmro CHEMICAL wonxs, mssouni, A conrona'rron or uxssoum.

PROCESS FOR PRODUCING SACGHJLRIN.

no Drawing.

Toni-u whom. it may concern 'Be it known that l, J wuss Bums, a citizen of the United States, residing at St. Louis,

Missouri, have invented a certain new and useful Improvement in Processes for Producing Saccharin, of which the following is a full, clear, and exact description, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to the manufacture of saccharin--benzosullinid, my present application being a continuation in part 0' my pending application Serial No. 359,809, filed February 19, 1920.

It is well known that saccharin is commonly produced by the oxidation of ortho toluene suliamid in an alkaline solution by means of potassium permanganate. 1 0ti1Sr sium permanganate is a costly reagent and at the present time is not readily available in large quantities. The object of my in- CH; c.s.

scum,

I-Ieretofore it was believedto be impossible to obtain saccharin by oxidation of ortho toluene sulfamid in an acid medium. Previous investigators oxidized the para and meta. toluene sulfonamid by means of d1- chromate sulfuric acid mixture to para and meta sulfamid benzoic acid, but failed to get results with ortho toluene sulfamid, and accordingly, concluded that oxidation with the dichromate sulfuric acid oxidizin mixture was limited to para and meta su stitution products. Remsen (Liebigs Annalen, vol. 178, age 298) and Noyes (American Chemical o'wmwl 8, 176485).

I have discovered that under suitable conditions ortho toluene sulfamid can be oxidized in an acid medium and that with suitable concentration and tem erature of the dichromate sulfuric acid mixture good yields of saccharin can be' obtained.

I have found that the concentration of the sulfuric acid used in this process is of the greatest importance. Too high a concentration causes considerable decomposition, and too low a concentration prevents the reaction altogether. In the experiments described in the ublications above referred to the relatively failure to obtain saccharin,

Specification of Letters Patent.

ow concentration caused the. because in said.

Patented Jan. 25, 1921.

Application filed September 7, 1920. Serial No. 408,499

vention is to provide a process for the man ufacture of saccharin which will be free from the objectionable feature of the process employed at present in the manufacture of saccharm, namely, the necessity of using potassium permanganate as the oxidizing agent.

M invention consists in roducin saccharin by oxidizing ortho to uene sul amid bymeans of an oxidizing 'mixture containmg chromic acid and sulfuric acid. The said oxidizing mixture can be produced by dissolving chromic acid in sulfuric acid or by mixing a chromate or a dichromate with sulfuric acid, it being preferable to use sulfuric acid of a concentration of at least 50% by weight and a temperature of reaction not higher than (1- Preferably, the oxidatlon of the ortho toluene sulfamid is eflected with a mixture of sodium dichromate and sulfuric acid in accordance with the following equation:

NH-i-NMSOrl-Cn(S04)a-l-6H:O

S01 experiments the sulfuric acid concentration of 33% by volume. Moreover, even if some saccharin had been obtained with this low concentration, it would have been estroyed a ain on account of the high teperature 0 oxidation which was brought about by heating on the steam bath and even boiling ofthe dichromate acid mixture.

In order to get a consistency of the oxidizing mass wh ch allows thorough stirring, it is necessary to use an excess of sulfuric acid over the amount theoreticall required. Instead of using an excess of su fur-1c acid neutral diluents may be used; organic solvents like glacial acetic acid or tetrachlorcarbon being particularly suitable for this pur ose.

.0 illustrate the my process I shall preferred procedure One kg. of ortho toluene sulfamid is fed under stirring into a mixture of 1.7 kg. so dium dichromate and 5 kg; sulfuric acid (50%) at ordinary temperature. On adding now slowly 2.7 kg. cmmentratcd sulfuric acid (98%) the oxidizing mixture had a practical operation of describe in detail the only about The temperature is controlled by by the flow of stirring and cooli of the mixture and also i e concentrated sulfuric acid. After addition of all of the acid the temperature may be allowed to rise-further in order to complete the reaction but care should be taken not to go above 70 C; Finally the maximum temperature is maintained for a couple of hours. After cooling down again to room temperature the crude saccharin containing some unoxidized amid is filtered from the chrome sulfate solution and washed with water. The separation of the saccharin and some ortho toluene sulfamid which may be present is carried out in the usual manner, by dissolving the saccharin with a sodium carbonate solution, filtering the amid and precipitating the saccharin from the filtrate with a mineral acid. I

In order to prevent any hydrolyzing or destructive act on of the excess sulfuric acid, a neutral solvent may be used in place of an excess of sulfuric acid to keep the mass sufliciently fluid, as described in the following procedure:

According to this modification, I may dissolve 1 kg. of ortho toluene sulfalnid in 2.7 k of concentrated sulfuric acid and add t is solution to a stirred solution of 1.7 kg. of sodium dichromate in 5.2 kg. glacial aceticacid. The additionof the ortho toluene sulfamid solution is regulated in such a way as to keep' the reaction temperature around C., the cooling is accomplished by means of a cooling water jacket, and after the addition of all the dichromate the temperature of 55 C. is maintained for several hours. While the oxidation is proceeding chromic sulfate and saccharin are precipiating from the solution and at the end of the oxidation these products are separated by filtration. The acetic acid is recovered by distillation of the filtrate. The chrome sulfate is dissolved from the saccharin with water and separated by filtration. The crude saccharin still contains some unoxidized ortho toluene sulfamid from which it can be so arated in the usual manner by dissolvin t e saccharin with a sodium carbonate so ution, filtering the amid andprecipihis tating the saccharin from the filtrate by acidification with a mineral acid.

While I have described two ways of practising my process, I wish it to be understood that the tem ratures and concentrabfi tions em loyed an the quantities of material use may be varied to a considerable extent without departing from the spirit of my invention.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A process for )roducing saccharin, characterized by oxidizing ortho toluene sultamid by means ofan oxidizing mixture containingchromic acid, dissolved in sulfuric acid of a concentration of at least 50% by weight and a temperature of reaction not higher than 75 C.

2. A process for producing saccharin, characterized by oxidizin ortho toluene sulfamid by means of an oxidizing mixture consisting of a chromate dissolved in sulfuric acid of a concentration of at least 50% by wei ht and a tem erature of reaction not hig er than 75 3. A process for producing saccharin, characterized by oxidizing ortho toluene sulfamid by means of an oxidizing mixture consisting of a dichromate dissolved in sulfuric acid of a concentration of at least 50% by weight and a tem rature of reaction not higher than 75 4; A process for producing saccharin,

characterized by oxidizing ortho toluene sulfamid by means of an oxidizing mixture consisting of sodium dichromate and sul furic acid of a concentration of at least 50% by wei ht and a tem erature of reac tion not big er than 75 5. A process for roducing saccharin, characterized by oxidizing ortho toluene sulfamid by means of an oxidizing mixture consisting of sodi'um dichromate dissolmed in sulfuric acid of a concentration of at least 50% by weight and a temperature of reaction not higher than 75 C. and using in addition to it a neutral solventas a diluent.

JULES BEBIE. 

